Charge receptacles for use in ion source units



Sept. 27, 1955 D. c. SEWELL 2,719,233

I CHARGE RECEPTACLES FOR USE IN ION SOURCE UNITS Filed Sept. 20, 1944 2 Sheets-Sheet l Filg. l

INVENTOR. @UAA/5 C. 55m/ELL n BYW ATTORNEY.

Sept. 27, 1955 D, C. SEWELL CHARGE RECEPTACLES FOR USE IN ION SOURCE UNITS Filed Sept. 20, 1944 2 Sheets-Sheet 2 @@@wwww Y INVENTOR. 00A/V5 C Sgn/ELL BY @Mw ATTORNEY.

United States Patent()l CHARGE RECEPTACLES FOR USE IN ION SOURCE UNITS Duane C. Sewell, Berkeley, Calif., assignor to the United States of America as represented by the United States Atomic Energy Commission Application September 20, 1944, Serial No. 554,926

7 Claims. (Cl. 25d-41.9)

The present invention relates to receptacle closures, and more particularly to charge receptacles for use in ion source units of the character of that employed in calutrons or the like.

It is an object of the invention to provide a charge receptacle of simple and rugged construction that may be used repeatedly in an ion source unit of the character mentioned.

Another object of the invention is to provide in an ion source unit a sealed charge receptacle embodying an improved closure arrangement facilitating ready opening of the' charge receptacle.

Another object of the invention is to provide a charge receptacle embodying a magnetically controllable closure member.

Another object of the invention is to provide a charge receptacle embodying a closure member and an arrangement governed jointly by'thermal and magnetic inuences for controlling the position of the closure member.

A further object of the invention is to provide an improved method of removing the cover from a charge receptacle, whereby the cover may be removed without physical contact therewith.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following speciiication taken in connection with the accompanying drawings, in which Figure l is a diagrammatic plan View of av calutron including an ion source unit in which there may be employed a charge receptacle em, bodying the present invention; Fig. 2 is a diagrammatic sectional view of the calutron taken along the line 2 2 in Fig. l; Fig. 3 is a longitudinal sectional View of the calutron ion source unit; Fig. 4 is a front elevational view of the source unit shown in Fig. 3; Fig. 5 is a sectional view of the source unit taken along the line 5 5 in Fig. 3; Fig. 6 is an enlarged fragmentary longitudinal sectional view of the charge receptacle employed in the source unit shown in Fig. 3 and embodying the present invention; Fig. 7 is an enlarged fragmentary longitudinal sectional view of a modified form of the charge receptacle; and Fig. 8 is an enlarged fragmentary longitudinal sectional view of another modified form of the charge receptacle.

At the outset, it is noted that a calutron is a machine of the character of that disclosed in the copending application of Ernest O. Lawrence, Serial No. 557,784, filed October 9, v1944, and is employed to separate the constituent u rice portion of the vapor is ionized causing ions of the several isotopes of the element to be produced; electrical means for segregating the ions from the un-ionized vapor and for accelerating the segregated ions to relatively high velocities; electromagnetic means for deflecting the ions along curved paths, the radii of curvature of the paths of the ions being proportional to the square roots of the masses of the ions, whereby the ions are concentrated in accordance with their masses; and means for de-ionizing and collecting the ions of the selected isotope thus concentrated, whereby to produce a deposit of the element enriched with the selected isotope.

Referring now more particularly to Figs. l and 2 of the drawings, there is illustrated a representative example of a calutron 10 of the character noted, that comprises magnetic field structure including upper and lower pole pieces y11 and 12, provided with substantially flat parallel spaced-apart pole faces, and a tank 13 disposed between the pole faces of the pole pieces 11 and 12. The pole pieces 11 and 12 carry windings, not shown, which are adapted to be energized in order to produce a substantially homogeneous and relatively strong magnetic field therebetween, which magnetic field passes through the tank 13 and the various parts housed therein. The tank 13 is of tubular configuration, being substantially crescentshaped in plan, and comprising substantially flat parallel spaced-apart top and bottom walls 14 and 15, upstanding curved inner and outer side walls 16 and 17, and end walls 18 and 19. The end walls 18 and 19 close the opposite ends of the tubular tank 13 and are adapted to be removably secured in place, whereby the tank 13 is hermetically sealed. Also, vacuum pumping apparatus 13a is associated with the tank 13, whereby the interior of the tank 13 may be evacuated to a pressure of the order of l0-5 to 10-4 mm. Hg. Preferably, the component parts of the tank 13 are formed of steel, the top and bottom walls 14 and 15 thereof being spaced a short distance from the pole faces of the upper and lower pole pieces 11 and 12 respectively, the tank 13 being retained in such position in any suitable manner, whereby the top and bottom walls 14 and 15 constitute in effect pole pieces with respect to the interior of the tank 13, as explained more fully hereinafter.

The removable end wall 18 suitably supports a source unit 20 comprising a charge receptacle 21 and a communicating arc-block 22. An electric heater 23 is arranged in heat exchange relation with Ithe charge receptacle 21 and is adapted to be connected to a suitable source of heater supply, whereby the charge receptacle 21 may be appropriately heated, the charge receptacle 21 being formed of steel or the like. The arc-block 22 is formed, at least partially, of carbon or graphite and is substantially C-shaped in plan, an upstanding slot 24 being formed in the wall thereof remote from the charge receptacle 21. Thus, the arc-block 22 is of hollow construction, the cavity therein communicating with the in- -terior of the charge receptacle 21.

Also, the removable end wall 18 carries a lamentary cathode 2,5 adapted to be connected to a suitable source of filament supply, the filamentary cathode 25 overhanging the upper end of the arc-block 22 and arranged in alignment with respect to the upper end of the cavity formed` therein. The arc-block 22 carries an anode 26 disposed adjacent the lower end thereof and arranged inalignment with respect to the cavity formed therein. Also, the arc-block 22 carries a collimating electrode 27 disposed adjacent the upper end thereof and having an elongated collimating slot 28 formed therethrough and arranged in alignment with respect to the lamentary cathode 25 as well as the anode 26 and the cavity formed in the arc-block 22. Both the anode 26 and the colli mating electrode 27 are electrically connected to the source unit 2t), which in turn is grounded; likewise, the tank 13 is grounded. Also, the ilamentary cathode 25 and the cooperating anode 26 are adapted to be connected to a suitable source of arc supply.

Further, the removable end wall 18 carries ion accelerating structure 29 formed of carbon or graphite and disposed in spaced-apart relation with respect to the wall of the arc-block 22 in which the slot 24 is formed. More specifically, a slit 30 is formed in the ion accelerating structure 29 and arranged in substantial alignment with respect to the slot 24 formed in the wall of the arcblock 22. A suitable source of accelerating electrode supply is adapted to be connected between the arc-block 22 and the ion accelerating structure 29, the positive and negative terminals of the supply mentioned being respectively connected to the arc-block 22 and to the ion accelerating structure 29. Further, the positive terminal of the accelerating electrode supply is grounded.

The removable end wall 19 suitably supports a collector block 31 formed of stainless steel or the like and provided with two laterally spaced-apart cavities or pockets 32 and 33 which respectively communicate with aligned slots 34 and 35 formed in the wall of the collector block 31 disposed remote from the removable end wall 19. It 'is noted that the pockets 32 and 33 are adapted to receive two constituent isotopes of an element which have been separated in the calutron 10, as explained more fully hereinafter. Further, `the inner wall 16 suitably supports a tubular liner 36 formed of copper or the like, rectangular in vertical cross-section, disposed within the tank 13 and spaced from the walls 14, 15, 16 and 17. One end of the tubular liner 36 terminates a'djacent the accelerating structure 29; and the other end of the tubular liner 36 terminates adjacent the collector block 31; the tubular liner 36 constituting an electrostatic shield for the high velocity ions traversing the curved paths between the slit 30 formed in the ion accelerating structure 29 and the slots 34 and 35 formed in the collector block 31, as explained more fully hereinafter. Finally, the tubular liner 36 is electrically connected to the ion accelerating structure 29 and to the collector block 31. Thus, it will be understood that the source unit 20 and the tank 13 are connected to the positive grounded terminal of the accelerating electrode supply; while the ion accelerating structure 29, the tubular liner 36 and the collector block l31 are connected to the negative Vungrounded terminal of the accelerating electrode supply; the ion accelerating structure 29, the tubular yliner 36 and the collector block 31 being electrically insulated from the component parts of the tank 13.

Considering now the general principle of operation of the calutron 10, a charge comprising ya compound of the element t'o be treated is placed inthe 'charge receptacle 21, the compound of the element mentioned Vbeing one which may be readily vaporized. The end walls 18 and 19 are securely attached to the open ends of the tank .13, whereby the tank l13 ishermetically sealed. The various electrical connections are completed and operation of the vacuum pumping apparatus 13a associated with the ltank 13 is initiated. When a pressure of the order of l0-5 to 10-4 mm. Hg is established within the tank 13, the electric circuits for the windings, not shown, associated with the pole pieces V11 and 12 are closed and adjusted, whereby a predetermined magnetic eld is established therebetween traversing the tank 13. The electric circuit for the heater 23 is closed, whereby the charge in the charge receptacle 21 is heated and vaporized. The vapor fills the charge receptacle 21 and is conductedinto the cornmunicating cavity formed in the arc-block 22. The electric circuit for the iilamentary cathode 25 is closed, whereby the tilamentary cathode is heated and rendered electron emissive. Then the electric circuit -between the flamentary cathode 25 and the anode 26 is closed, whereby an arc discharge is struck therebetween, electronsjproceeding from the filamentary cathode 25 through the collimating slot 2S formed in the collimating electrode 27 to the anode 26. The collimating slot 28 formed in the collimating electrode 27 defines the cross-section of the Stream of electrons proceeding into the arc-block 22, whereby the arc discharge has a ribbon-like configuration and breaks up the molecular form of the compound of the vapor to a considerable extent, producing positive ions of the element that is to be enriched with the selected one of its isotopes.

The electric circuit between the arc-block 22 and the ion accelerating structure 29 is completed, the ion accelerating structure 29 being at a high negative potential with respect to the arc-block 22, whereby the positive ions in the arc-block 22 are attracted by the ion accelerating structure 29 and accelerated through the voltage impressed therebetween. More particularly, the positive ions proceed from the cavity formed in the arc-block 22 through the slot 24 formed in the wall thereof, and across the space between the ion accelerating structure 29 and the adjacent wall or the arc-block 22, and thence through the slit 30 formed in the ion accelerating structure 29 into the interior of the tubular liner 36. The high-velocity positive ions form a vertical upstanding ribbon or beam proceeding from the cavity formed in the arc-block 22 through the slot 24 and the aligned slit 30 into the tubular liner 36.

As previously noted, the collector block 31, as well as the tubular liner 36, is electrically connected to the ion accelerating structure 29, whereby there is an electricfield-free Ipath for the high-velocity positive ions disposed between the ion accelerating structure 29 and the collector block 31 within the tubular liner 36. The high-velocity positive ions entering the adjacent end of the liner 36 are deflected from their normal straight-line path and from a vertical plane passing through the slot 24 and the aligned slit 30, due to the effect of the relatively strong magnetic eld maintained through the space within the tank 13 and the liner 36 through which the positive ions travel, whereby the positive ions describe arcs, the radii of which are proportional to the square roots of the masses of the ions and consequently of the isotopes of the element mentioned. Thus, ions of the relatively light isotope of the element describe an interior arc of relatively short radius and are focused through the slot 34 into the pocket 32 formed in the collector block 31; whereas ions of the relatively heavy isotope of the element describe an exterior arc of relatively long radius and are focused through the slot 35 into the pocket 33 formed in the collector block 31. Accordingly, the ions of the relatively light isotope of the element are collected in the pocket 32 and are deionized to produce a deposit of the relatively light isotope of the element therein; while the ions of the relatively heavy isotope of the element are collected in the pocket 33 and are de-ionized to produce a deposit of the relatively heavy isotope of the element therein.

After all of the charge in the charge receptacle `21 has been vaporized, all of the electric circuits are interrupted andthe end wall 18 is removed so that another charge may be placed in the charge receptacle 21 and subsequently vaporized in the manner explained above. After a suitable number of charges have been vaporized in order to obtain appropriate deposits of the isotope of the'element in the pockets 32 and 33 of the collector block 31, the end wall 19 may be removed and the deposits lof the collected isotopes in the pockets 32 and 33 in the collector block 31 may be reclaimed.

Of course, it will be understood that the various dimensions of the parts ofthe calutron 10, the 'various electrical potentials applied between the various electrical parts thereof, as well as the strength of the magnetic field between the pole pieces 11 and 12, are suitably'correlated with respect to each other, depending upon the mass numbers of the several isotopes of the element which is to be treated therein. In this connection reference is again made to the copending application of Ernest O. Lawrence, for a complete specification of a calutron especially designed for the production of uranium enriched with vthe isotope U2. By way of illustration, it is` noted that when the ealutron is employed in order to produce uranium enriched with U235, the compound of uranium which is suggested asa suitable charge in the charge receptacle 21 is UC14, as this compound may be readily vaporized and the molecular form of the vapor may be readily broken up to form positive ions of uranium with great facility. In this case, uranium enriched with U235 is collected in the pocket 32 of the collector block 31, and uranium comprising principally U238 is collected in the pocket 33 of the collector block 31. Also, it is noted that from a practical standpoint, the deposit of uranium collected in the pocket 32 of the collector block 31 contains considerable amounts of Um, in View of the fact that this isotope comprises the dominant constituent of normal uranium. Furthermore, the deposit of uranium collected in the pocket 32 of the collector block 31 contains a considerably increased amount of U234, in View of the fact that it is not ordinarily feasible to separate U234 and U235 in the production of relatively large quantities of uranium enriched with U235 for commercial purposes. Accordingly, in this example the uranium deposited in the pocket 32 of the collector block 31 is considerably enriched, both with U234 and with U235, and considerably impoverished' with respect to U233 as compared to natural or normal uranium.

Referring now more particularly to Figs. 3 to 5, inelusive, of the drawings, there are illustrated the' structural details of the source unit which is arranged in the magnetic field between the pole pieces of the calutron in the manner previously explained, the source unit 20 comprising the charge receptacle 21 and the arc-block 22. The charge receptacle 21 comprises wall structure, including a removable cover 50, dening an upstanding cylindrical cavity or reservoir 51 therein, that is adapted to receive a removable cylindrical charge bottle 52 embodying the features of the present invention and containing a charge 53 which it to be vaporized. The arc-block 22 comprises wall structure defining an upstanding distributing chamber 54 and an upstanding are chamber 55 therein, the cavity 51 communicating with the distributing chamber 54 through a tubular member 56 supported by the Wall structure of the charge receptacle 21 and the wall structure of the arc-block 22. The wall structure of the charge receptacle 21 carries the exteriorly arranged electric heater 23 of any suitable form, whereby the charge receptacle 21 and consequently the charge bottle 52 may be appropriately heated in order to vaporize the charge f 53 contained in the charge bottle 52. Similarly, the wall structure of the arc-block 22 carriesan exteriorly arranged electric heater 57 of any suitable form, whereby the arc-block 22, and more particularly the distributing chamber 54 therein, may be heated in order to prevent condensation of the contained vapor, as explained more fully hereinafter.

More particularly, the wall structure of the arc-block 22 comprises ai substantially inverted U-shaped frame member 58, supporting' an upstanding baiiie plate 59, the frame member 5S and thev baie plate 59 being formedof carbon or graphite. The frame member 58 is secured to' the wall structure of the arc-block 22 by an arrangement comprising` two upstanding strips 60, and comprises a top` wall 61, two upstanding substantially parallel spacedapart side walls 62, and a front wall 63, the front wall 63 having the centrally disposed longitudinal sloty 24 formed therein and communicating With the arc chamber 55. The side edges of the bathe plate 59 are spaced a short distance from the side walls 62 of the frame member 58 in order toprovide communication between. the distributing chamstandard 64 which supports cathoderstructure 65 incooperating relationship with respect to the arc-block 22. More particularly, the cathode structure 65 comprises two terminals 66 supporting the opposite ends of the substantially U-shaped filamentary cathode 25, the opposite ends of the filamentary cathode 25 being removably clamped in place by the respective terminals 66, and the two terminals being connected to the suitable source of filament supply, as previously noted. The central portion of the tilarnentary cathode 25 overhangs the central portion of to top wall 61 of the frame member 58, the top wall 61 having a transversely extending slot 67 formed therethrough communicating with the arc chamber 55. The upper end of the transverse slot 67 is provided with a' counter recess 63 extending thereabout which receives the collimating electrode 27, the collimating electrode 27 having the transversely extending slot 28 formed therethrough, as previously noted, and communicating with the transverse slot 67 formed in the top wall 61 and consequently with the are chamber 55. More particularly, the filamentary cathode 25 is spaced a short distance above the collimating electrode 27, the central portion of the filameutary cathode 25 being arranged in alignment with the transverse slot 28 formed in the collimating electrode 27. Further, a laterally extending slot 69 is formed in the front wall 63 of the frame member58 adjacent the lower end thereof, and the anode 26 is securely fitted therein in position to extend into the arc chamber in alignment with the central portion of the filamentary cathode 25 and the transverse slot 28 formed in the collimating electrode 27 The negative and positive terminals of the are supply are respectively connected to the filamentary cathode 25 and to the arc-block 22, the anode 26 and the collimating electrode 27 being connected together by the frame member 58, and consequently by way of the arc-block 22 to the positive terminal of the are supply mentioned, as previously noted. Finally, a shield 70 is supported by one of the terminals 66 and extends laterally over the upper surface of the central portion of the filamentary cathode 25 in'order to prevent migration of the electrons emitted by the filamentary cathode 25 upwardly in the longitudinal direction.

Considering now the detailed operation of the source unit 20, when the electric circuit for the heater 23 is completed, the charge receptacle 21 and consequently the charge bottle 52 are heated, whereby the charge 53 is vaporized, filling the cavity 51 in the charge receptacle 21. The vapor passes through the tubular member 56 into the distributing chamber 5:3, whereby this chamber is filled with the vapor. The vapor is thoroughly mixed in the distrlbuting chamber 54 and passes around the side edges of the baiiie plate 59 into the arc chamber 55, whereby this chamber is filled with the Vapor. More particularly, the arc chamber 55 is thoroughly and uniformly filled with the vapor to be ionized, due to the arrangement of the distributing chamber 54 and the bafiie plate 59.

When the circuit for the filamentary cathode 25 is completed, the lamentary cathode 25 is heated and rendered electron` emissive; and when the arc supply circuit is completed between the iilamentary cathode 25 and the arc'- bloek 22, electrons are projected from the central portion of the filamentary cathode 25 toward the collimating electrode 27. More particularly, some of these electrons pass through the transverse slot 23 formed in the collimating electrode 27 into the arc chamber 55 and proceed toward the anode 26. Accordingly, the collimating electrode 27 causes a stream of electrons having a ribbon-like configuration to be projected through the are chamber 55, whereby the vapor in the are chamber 55 is ionized. The positive ions produced in the are chamber 55 are drawn through thev upstanding slot 24 formed in the front wall 63 of the frame member 58 by the associatedion accelerating structure 29, whereby the beam of positive ions having a. substantially ribbon-like coniiguration is projectedintol the adjacent end of the associated liner 36 and directed toward the cooperating collector block 31.

Referring now to Figs. 3, and 6 of the drawings, the charge bottle 52 there illustrated constitutes a receptacle and comprises a body including a relatively thick bottom wall 80, a relatively thick top wall 81 and an upstanding cylindrical side wall 82, all formed of relatively nonmagnetic material. Preferably, the walls 80, 81 and 82 are formed of stainless steel and securely welded together. A centrally disposed annular opening or aperture 83 is formed in the top wall 81 in order to provide communication between the interior of the charge bottle 52, wherein the charge S3 is contained, and the cavity 51 formed in the charge receptacle 21, as clearly indicated in Figs. 3 and 5. Also, an annular recess or groove 84 is formed in the top surface of the top wall 81 concentric with and surrounding the aperture 83. Further, the charge bottle 52 comprises a cover or closure member 85 including a top Wall 86 and a downwardly extending cylindrical flange or rim 87, formed of magnetic material.

Preferably, the cover 85 is formed of steel or soft iron and is of one-piece construction. The cover 85 has a normal position wherein the downwardly extending flange 87 is disposed within the annular groove 84, and sealed in place by an annular body of thermoplastic material 88. Preferably, the body of thermoplastic material 88 comprises Woods metal normally bonded to the adjacent surface of the top wall 81 lining the groove 84 and the adjacent surface of the liange 87. Preferably, the cooperating surfaces mentioned are provided with a thin layer of silver or the like, whereby the surfaces mentioned are coated in order to insure a fluid-tight joint between the body of the charge bottle 52 and the cover 85. Thus, the body of the charge bottle 52 is of symmetrical cylindrical configuration about the center line thereof. On the other hand, the top wall 86 of the cover 85 is inclined at an angle of other than ninety degrees with respect to the center line of the body of the charge bottle 52 when the cover 85 occupies its normal position, whereby the cover 85 is of asymmetrical cylindrical configuration about the center line of the body of the charge bottle 52. For purposes of illustration, in Fig. 6 the center line of the body of the charge bottle 52 is indicated at 89; while a plane passing through the center of magnetic mass of the top wall 86 of the cover 85 is indicated at 90, the plane 90 being inclined with respect to the center line 89. Specifically, the plane 90 is inclined at an angle of approximately 10 with respect to the top wall 81 of the charge bottle 52.

Considering now the construction and arrangement of the charge bottle 52 with reference to its operation in the source unit 20, it is noted that in the example illustrated the charge bottle 52 is filled with a charge 53 comprising the compound UCl4, evacuated and hermetically sealed, all prior to use. The previously prepared charge bottle 52 containing the charge 53 is then placed in the cylindrical cavity 51 formed in the charge receptacle 21, and the cover 50 thereof is secured in place. The tank 13 of the calutron 10 is then closed and operation thereof is initiated in the manner previously explained. Accordingly, the charge bottle 52 is supported in a-given position in the source unit and consequently inthe tank 13 of the calutron 10. Subsequently, when the pressure in the tank 13 is lowered to the order of l0-5 toflOr1 mrn. Hg, the electric circuits for the windings, not shown, associated with the pole pieces 11 and 12 are closed and adjusted in order to establish a predetermined magnetic field therebetween, traversing the tank 13, as previously noted. The magnetic field traversing the tank 13 permeates the body of the charge bottle 52, the center line 89 of the body being aligned with respect to the magnetic field mentioned. Accordingly, the normal position of the cover 85 closing the aperture 83 in the top wall 81 of the charge bottle 52 constitutes a position of magnetic instability, in view of the fact that the top wall 86 of the cover 85 is inclined with respect to the top wall 81 of the charge bottle 52, the plane 90 being inclined with respect to the center line 89, as previously noted. Hence the magnetic field acts upon the cover 85, producing a magnetic moment tending to rotate the cover in a counter-clockwise direction, as viewed in Figs. 3 and 6, about the lower left-hand edge of the rim 87 thereof. At this time the cover 85 is not moved from its normal position due to the magnetic moment mentioned, in view of the fact that it is securely sealed in place by the body of thermoplastic material 88.

Subsequently, when the electric circuit for the heater 23 is closed, the charge receptacle 21 is heated, whereby the charge bottle 52 is heated. When the charge bottle 52 is thus heated, the heat is conducted through the top wall 81 thereof into the body of thermoplastic material 88, whereby this body is softened, releasing the rim 87 of the cover S5. When the cover is thus released, the previously mentioned magnetic moment becomes effective, and the cover 85 is rotated in the counter-clockwise direction away from its normal position to an operated position opening the aperture 83 formed in the top wall 81. Thus, when the cover 85 is moved from its normal position to its operated position under the joint control of the magnetic field between the pole pieces 11 and 12 and the body of thermoplastic material 88, the interior of the charge bottle 52 is placed in communication through the aperture 83 with the cavity 51 in the charge receptacle 21, whereby the charge 53 contained in the charge bottle 52 is vaporized and conducted through the aperture 83 into the cavity 51, and thence through the tubular member 56 into the distributing chamber 54, as previously explained.

Subsequently, when operation of the calutron 10 is arrested, the circuits for energizing the windings, not shown, associated with the pole pieces 11 and 12, as well as the circuit for the electric heater 23, are interrupted, whereby the charge bottle 52 is no longer disposed in a magnetic field and is no longer heated. Accordingly, at this time the magnetic moment mentioned is no longer exerted upon the cover 85, whereby the cover 85 falls, due to the action of gravity, back to its normal position. More specifically, the cover 85 is moved from its operated position shown in Figs. 3 and 5 to its normal position shown in Fig. 6, the cover 85 being rotated in the clockwise direction as indicated in Figs. 3 and 6. When the cover 85 is thus returned by the action of gravity to its normal position, the flange 87 re-enters the groove 84 formed in the top wall 81, and is embedded in the body of molten thermoplastic material 88. Subsequently, when the charge bottle 52 is cooled sufficiently, the body of thermoplastic material 88 again sets, thereby again hermetically to seal the charge bottle 52.

Referring to Fig. 7 of the drawings, a modified form of the charge bottle 92 is illustrated which is substantially identical to the charge bottle 52 previously described, except that it is provided with a cover 93 of slightly different construction. Specifically, the cover 93 is formed of magnetic material, such, for example, as steel or soft iron, and is of one-piece construction, comprising an inclined top wall 94 and a downwardly extending cylindrical fiange or rim 95, the top wall 94 being of tapered cross-section and consequently of varying thickness from left to right, as indicated. As illustrated, the center line of the body of the charge bottle 92 is indicated at 96; while the plane passing through the center of magnetic mass of the top wall 94 of the cover 93 is indicated.

at 97, the plane 97 being inclined with respect to the center line 96. Accordingly, the body of the charge bottle 92 is cylindrical and symmetrical with respect to.

magnetic material, as well as the relative construction of the charge bottle 92 and the cover 93, the normal. position of the cover 93 is one of magnetic instability when the charge bottle 92 is placed in the charge receptacle 21 in the source unit 20 in the magnetic field traversing the tank 13 of the calutron 10. Accordingly, the operation of the charge bottle 92 in conjunction with the source unit 20 of the calutron is virtually the same as that previously described in connection with the charge bottle 52.

Referring to Fig. 8 of the drawings, a further modified form of the charge bottle 102 is illustrated which is substantially identical to the charge bottle 52 previously vdescribed, except that it is provided with a top wall 101 of slightly different construction. Specifically, the top wall 101 is inclined with respect to the center line of the body of the charge bottle 102. Also, the charge bottle 102 comprises a cover 103 formed of magnetic material, such, for example, as steel or soft iron, and is of onepiece construction, comprising a top wall 104 and a downwardly extending cylindrical flange or rim 105. As illustrated, the center line of the body of the charge bottle 102I is indicated at 106; while the plane passing through the center of magnetic mass of the top wall 104 of the cover 103 is indicated at 107, the plane 107 being inclined with respect to the center line 106. Accordingly, the body of the charge bottle 102 is cylindrical and symmetrical with respect to` the center line 106; while the cover 103 is cylindrical and asymmetrical with respect to the center line 106, due to the inclination of the top wall 101.

In view of the facts that the body of the charge bottle 102 is formed of non-magnetic material (such, for example, as stainless steel) and the cover 103 is formed of magnetic material, as well as the relative construction of the charge bottle 102 and the cover 103, the normal position of the cover 103 is one of magnetic instability when the charge bottle 102 is placed in the charge receptacle 21 in the source unit 20 in the magnetic field traversing the tank 13 of the calutron 10. Accordingly, the operation of the charge bottle 102 in conjunction with the source unit of the calutron 10 is virtually the same as that previously described in connection with the charge bottle 52.

While it is preferable that the covers 85, 93 and 103 of the charge bottles 52, 92 and 102, respectively shown in Figs. 6, 7 and 8 of the drawings, be formed of steel or iron and be of one-piece construction, it will be appreciated, of course, that this construction is not essential as long as the cover comprises a magnetically responsive portion constituting an armature. For example, any one of the covers may comprise an integral top wall and a downwardly extending fiange formed of non-magnetic material, such `as stainless steel, the top wall carrying an armature formed of magnetic material such as steel or soft iron. This can be accomplished in a ready manner, in view of the fact that the top wall of each of the covers is thicker than the downwardly extending flange thereof. In this alternative arrangement, the top wall of the cover proper would have the armature secured thereto in any suitable manner, such, for example, as by welding.

In view of the foregoing, it is apparent that a source unit for a calutron has been provided which comprises a charge receptacle receiving a removable hermetically sealed charge bottle of improved construction and arrangement, whereby the charge bottle may be opened after it has been placed in the charge receptacle in the source unit and operation of the calutron has been initiated. Moreover, this improved arrangement utilizes the normally existent magnetic field in the calutron to accomplish the end mentioned, whereby auxiliary manipulative devices are not required. Furthermore, the charge bottle is preserved in its originally packed condition during operation of the calutron, thereby to insure operation of the calutron under uniform and standard operating conditions. The last-mentioned feature is very advantageous, in view of the fact that the chargenormallycontained in the charge bottle comprises a uranium halide, such, for example, as UCL; which is very hygroscopic. Finally, it will be understood that the charge bottle may be employed in the calutron repeatedly, as it may readily be removed from the source unit after a charge therein has been vaporized, and refilled and vacuumA sealed again for use.

While there has been described what is at presentconsidered to be the preferred embodiment of the invention, it will be understood that various modifications maybe made therein and it is intended to cover inthe appended claims all such modifications as fall Within the true spirit and scope of the invention.

What is claimed is: Y

l. In combination with a calutron comprising a closed tank adapted to be permeated by a magnete field and housing an ion source unit including structure providing a charge reservoir and communicating charge ionizing chamber; a normally closed receptacle containing a charge and positioned within said charge reservoir, said receptacle having an aperture in a wall thereof for communication between said receptacle and said charge reservoir, and a movable cover for said charge receptacle comprising an armature and having anormal position of magnetic instability in closing relationship with said aperture whereby establishmentof said magnetic field moves said cover to an operated .position out of closing relationshipl with said aperture, whereby the charge in said receptacle fills said charge reservoir and enters said communicating charge ionizing chamber.

2. A device comprising a support, a receptacle carried by said support, means for producing a magnetic field permeating said receptacle, means for heating said receptacle, said receptacle including a wall having an aperture therein, a magnetically responsive member having a normal position in closing relation to said aperture and an operated position out of closing relation to said aperture, the normal position of said member constituting a position of magnetic instability whereby said magnetically responsive member is governed by said magnetic field for moving said member from its normal position to its operated position, and thermally responsive means governed by the temperature of said receptacle for controlling said magnetically responsive member.

3. A device comprising means for producing a magnetic field, a receptacle positioned in said magnetic field, said receptacle including a wall having an aperture therein, a magnetically responsive member having a normal position closing said aperture and an operated position out of closing relation to said aperture, the normal position of said member constituting a position of magnetic instability whereby said member moves from its normal to operated position under the influence of said magnetic field, thermally responsive means normally sealing said member to said wall and thereby limiting the operation of said magnetically responsive element, and heating means about said receptacle serving to govern the sealing action of said thermally responsive means selectively to terminate the limiting action thereof upon said magnetically responsive element.

4. A device comprising means establishing a magnetic eld, a receptacle supported within said field, means for heating said receptacle, said receptacle including a wall having an aperture therein, a magnetically responsive element having a normal position closing said aperture, a body of thermoplastic material normally sealing said member to said wall in its normal position, the normal position of said member constituting a position of magnetic instability, whereby said member is movable from its normal position closing said aperture to an operated position out of closing relation to said aperture as limited by the adhesive property of said thermoplastic material.

5. A device including a substantially fiuid-tight casing, means producing a magnetic field through said casing,

and a receptacle adapted to be supported in a given position within said casing, said receptacle comprising a body formed of nonmagnetic material including wall structure having an aperture therein, said wall structure being inclined with respect to the center line of said body, and a cover formed of magnetic material carried by said wall structure and having a normal position closing said aperture, said cover including a top wall disposed substantially parallel to said wall structure, the normal position of said cover constituting a position of magnetic instability when said receptacle is supported in said given position in said given magnetic field owing to the inclination of said wall structure with respect to the center line of said body, whereby said cover is movable from its normal position to an operated position opening said aperture by the action thereon of said magnetic eld.

6. In combination with a calutron comprising a closed tank permeable by a magnetic eld and housing an ion source unit including structure providing a charge reservoir and communicating charge ionizing chamber; a charge bottle formed of substantially non-magnetic material and removably positioned within said charge reservoir, said charge bottle having an aperture in a wall thereof, a cover in closing relation to said aperture, said cover having a top wall and side walls and being formed of a magnetic material, the top wall of said cover being inclined with respect to said magnetic eld whereby said magnetic eld exerts a torque thereon to move said cover from its normal position to an operated position out of closing relation with said aperture thereby providing communication between the interior of said charge bottle and said charge receptacle.

7. In combination with a calutron comprising a closed tank permeated by a magnetic eld and housing an ion source including structure providing a charge reservoir and communicating charge ionizing chamber; a normally closed receptacle containing a charge and positioned within said charge reservoir, a magnetically responsive cover for said receptacle having a normal position in closing relation thereto, said cover having a nonuniform cross section and constituting an armature in a position of magnetic instability whereby said cover is moved from a normal position closing said receptacle to an operated position out of closing relation with said receptacle by the action of said magnetic eld.

References Cited in the le of this patent UNITED STATES PATENTS 712,447 Woolley Oct. 28, 1902 1,369,919 Eliel Mar. 1, 1921 1,507,884 Engler Sept. 9, 1924 2,053,930 Winter Sept. 8, 1936 2,285,622 Slepian June 9, 1942 2,355,658 Lawlor Aug. 15, 1944 

